|Country||Croatia, Bosnia and Herzegovina|
|Main source||Stražbenica mountain, Croatia|
|River mouth||Jasenovac, Croatia|
|Length||212 km (132 mi)|
The source of the Una is the Una spring, also known as Vrelo Une, and is located on the north-eastern slopes of the Stražbenica mountain in Lika region, Croatia. After 4 km the river reaches Bosnia and Herzegovina at the confluence with the Krka River. From here the Una river forms a natural border between Croatia and Bosnia for the next 8.5 km until it reaches the rail bridge 1.5 km before the Bosnian town of Martin Brod. From the rail bridge the Una enters Bosnia completely and flows for 21 km, before reaching the border between the two countries for the second time, 9 km downstream town of Kulen Vakuf. From here it forms the border for the next 20 km, all the way to another rail bridge between the villages of Malo Seoce and Užljebić. Here the Una enters Bosnia completely for the second time, and near Ripač it winds more north-westwards, entering Bihać, and turning north to Bosanska Krupa and Bosanska Otoka. After 85 km of flowing through Bosnia, the Una again marks the border between Bosnia and Herzegovina and Croatia for the third and final time, near the villages of Dobretin and Javornik (Croatia). It maintaining that status for the rest of its course until confluence with the Sava. At this stage, the Una passes by the Bosnian towns of Bosanski Novi (Novi Grad), Bosanska Kostajnica, Bosanska Dubica, and Croatian towns of Dvor, Hrvatska Kostajnica, Hrvatska Dubica. It spills into the Sava River near small town of Jasenovac.
The Una is a right tributary of the Sava river and the main tributaries are the Unac River, the Sana, the Klokot River and the Krušnica River. The hydrological parameters of Una are regularly monitored in Croatia at Kostajnica.
Flora and fauna
Over 170 types of medicinal herbs grow by the Una River; a rare plant called Campanula unensis, the "Una bluebell", was named after the Una river's bright turquoise and green colors. 28 kinds of fish live in this river and the biggest of which is the huchen (mladica, scientific name: Hucho hucho).
There is also an annual event held on the river, the "International Una Regatta", where people would go down the river in boats and kayaks from Kulen Vakuf, with excursion to Vrelo Une in Croatia, with the climax in Bihać. The Regatta is a sort of celebration for the river itself, rather than a boat race.
Una National Park
Una National Park was established 2006 around the Upper Una River and Unac River. It's a Bosnia and Herzegovina’s most recently established National Park, of only three existing in the country so far. The main purpose of the park is to protect unspoiled Una and Unac rivers which runs through it. Protection zone of the National Park stretches on the western side from the source of the Krka River and its course to the confluence with the Una on the state border of Bosnia and Herzegovina with Croatia from where park border follows the Una and state border to the town of Martin Brod and confluence with the Unac. On the eastern side border of the park goes from the entrance of the Unac River into its canyon, few kilometers downstream from town of Drvar, and follows the Unac and its canyon all the way to the confluence with the Una in town of Martin Brod. From there park border follows the Una on the right and state border between Bosnia and Herzegovina and Croatia on the left, until it reach a small town of Ripač, few kilometers upstream from town of Bihać.
The Una’s stunning waterfalls and white water rapids highlight the park. The most famous waterfalls are those at Martin Brod, where the popular "International Una Regatta" kayaking competition begins, and Štrbački Buk further downstream. Throughout the park, visitors can enjoy prime conditions for rafting, fishing, cycling, hiking, and camping. Jumping from the city bridges in Bihać and Bosanska Krupa is also popular.
Una National Park is also noted for its biodiversity, with 30 fish species, 130 bird species, and other animals, including lynx, fox, wolf, bear and chamois.
Area of the park has rich cultural-historic heritage and numerous archaeological sites, many dating from the prehistoric period. Among the historical treasures of the region are the Roman fort Milančeva Kula, Rmanj Monastery, many medieval fortresses like Oštrovica medieval fortress above Kulen Vakuf and the Ostrožac Castle, to name just a few.
Proximity to Plješivica mountain virgin forest, which stretches between Bosnia and Herzegovina and Croatia, and Croatia’s Plitvice Lakes National Park makes Una National Park a top destination for visitors. More importantly, all of the facts about these two National Parks, their proximity, natural, cultural and historical richness, brings out the possibility and makes viable idea of joint management and promotion  Una Republic
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- Ostroški, Ljiljana, ed. (December 2015). Statistički ljetopis Republike Hrvatske 2015 [Statistical Yearbook of the Republic of Croatia 2015] (PDF). Statistical Yearbook of the Republic of Croatia (in Croatian and English) 47. Zagreb: Croatian Bureau of Statistics. p. 49. ISSN 1333-3305. Retrieved 27 December 2015.
- "Daily hydrological report". State Hydrometeorological Bureau of the Republic of Croatia. Retrieved 2010-09-09.
- "Peace Park Plitvice-Una: New Bridge between Bosnia-Herzegovina and Croatia". newsvine.com. 2011. Retrieved 2012-04-04.
Media related to River Una (Sava) at Wikimedia Commons